Transobturator lead implantation for pelvic floor stimulation

ABSTRACT

The disclosure is directed to a method and tool for implanting a stimulation lead or other medical device adjacent a pudendal nerve. The tool includes a shaped needle that enters a patient and passes through an obturator foramen passage in a pelvis. A physician places a tip of the tool at the pudendal nerve and performs test stimulation to confirm an effective stimulation location. A shape memory cannula initially covering the needle remains at the pudendal nerve when the physician removes the tool. The cannula deforms to follow the curve of the pudendal nerve once the needle is removed, and a lead is inserted into the cannula and secured at the pudendal nerve placement site. This method may provide an easier and more consistent procedure for implanting the stimulation lead near the pudendal nerve.

This application is a continuation of U.S. patent application Ser. No.11/338,611, which is entitled, “TRANSOBTURATOR LEAD IMPLANTATION FORPELVIC FLOOR STIMULATION,” and was filed Jan. 24, 2006. The entirecontent U.S. patent application Ser. No. 11/338,611, which published asU.S. Patent Application Publication No. 2007/0173900 on Jul. 26, 2007,is incorporated herein by reference in its entirety.

TECHNICAL FIELD

The disclosure relates to medical devices and, more particularly,surgical implantation tools.

BACKGROUND

Urinary incontinence, sexual dysfunction, and other pelvic floordisorders are common problems afflicting people of all ages, genders,and races. Many of the disorders may be associated with aging, injury orillness. In some cases, pelvic floor disorders can be attributed toimproper nerve function. For example, aging can often result in nervedisorders that prevent proper operation of the bladder, sphinctermuscles, or sexual organs. Nerves, such as the sacral nerve, pudendalnerve, or branches of the pudendal nerve, running though the pelvicfloor regulate urinary and sexual function. Urinary incontinence orsexual dysfunction can arise when there is breakdown in communicationwithin the nervous system.

Electrical stimulation of nerves in the pelvic floor may provide aneffective therapy for a variety of disorders. For example, a surgeon mayimplant an electrical stimulation lead adjacent to the sacral nerve,pudendal nerve, or branches of the pudendal nerve. An implantableneurostimulator may be provided to deliver electrical stimulationthrough the lead. The stimulation may induce urinary sphincterconstriction or reduce bladder wall constriction to aid the patient inreducing unwanted urinary voiding. Also, the stimulation may beeffective in restoring sexual function or alleviating pelvic floor pain.Stimulation leads are ordinarily implanted surgically or percutaneously.

SUMMARY

The disclosure is directed to a method and tool for implanting astimulation lead or other implantable medical device adjacent a pelvicnerve, such as the pudendal nerve. The tool includes a shapedintroducer, such as a needle, that enters a patient and passes through apassage in a pelvis, such as the obturator foramen. A physician places atip of the tool at the target nerve site and performs test stimulationto confirm an effective stimulation location.

A cannula initially covering the introducer remains at the nerve sitewhen the physician removes the introducer. The cannula may have a shapememory property that permits it to deform to follow the curve of thepudendal nerve once the introducer is removed. A lead or otherimplantable medical device is inserted into the cannula and secured atthe pudendal nerve placement site. This transobturator placement methodmay provide an easier and more consistent procedure for implanting astimulation lead or other medical device near the pudendal nerve orother pelvic nerves.

Electrical stimulation of the pudendal nerve may provide therapy forpatients experiencing urinary incontinence, urinary retention, boweldisorders such as fecal incontinence, constipation, sexual dysfunction,or other pelvic floor disorders related to pelvic nerve function.Alternatively, therapeutic stimulation may be induced by delivery ofdrugs or other substances. The transobturator procedure described hereinmay also be directed to the implantation of electrical leads adjacentother pelvic floor nerves. For example, the nerve of the clitoris may beaccessed and stimulated to treat sexual dysfunction. In addition, thetransobturator procedure may be applied to female or male patients.

In one embodiment, the disclosure provides a method for placing animplantable medical device in a pelvis of a patient, the methodcomprising creating a path through an opening in the pelvis, wherein theopening in the pelvis is an obturator foramen, and placing theimplantable medical device via the path so that the implantable medicaldevice is disposed adjacent to a nerve.

In another embodiment, the disclosure provides a system for placing animplantable medical device in a pelvis of a patient, the systemcomprising a handle, a needle, coupled to the handle, for insertionthrough an obturator foramen of the pelvis, and a cannula of a firstshape having an inner lumen that receives at least a portion of theneedle, wherein the needle is curved to facilitate insertion through theobturator foramen to extend to a nerve within the pelvis.

In an additional embodiment, the disclosure provides a method forplacing an implantable lead for an electrical neurostimulator in apelvis of a patient. The method comprises creating a path through anopening in the pelvis with a needle, wherein the opening in the pelvisis an obturator foramen, placing a cannula over the needle, introducingthe cannula into the path, withdrawing the needle from the cannula, andinserting the implantable lead into the cannula so that the implantablemedical device is disposed adjacent to a nerve.

In various embodiments, the disclosure may provide one or moreadvantages. For example, the transobturator implantation procedure mayprovide an easier and more consistent procedure for implanting thestimulation lead near the pudendal nerve. For example, thetransobturator approach presents a number of anatomical landmarks, suchas bone, muscle and ligament structures, that may be helpful in guidingan implantation tool to the desired nerve site. The transobturatorimplantation procedure may also reduce the risk of nerve tissue damageassociated with other lead implantation procedures. In addition, animproved implantation procedure may not only decrease the time and costassociated with lead implantation, but increase the number of patientswho may utilize pudendal nerve or other pelvic floor nerve stimulationto treat a variety of conditions. Further, transobturator implantationmay utilize established skills of the physician. Additional advantagesmay include more secure placement of a lead, and resistance to movementof the lead due to placement through the obturator membrane. Also, theremay be less chance of movement during activity such as intercourse withpudendal or clitoral nerve stimulation following lead implantation viathe transobturator route. In some cases, external imaging techniquessuch as fluoroscopy may be unnecessary to achieve proper lead placement.

The details of one or more embodiments of the disclosure are set forthin the accompanying drawings and the description below. Other features,objects, and advantages of the disclosure will be apparent from thedescription and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram illustrating an exemplary implant tool andmethod of inserting the tool through an obturator foramen of the pelvisfor implantation of a medical device such as an electrical stimulationlead.

FIG. 2 is a schematic diagram illustrating the implant tool of FIG. 1upon insertion through the obturator foramen to reach a pudendal nerve.

FIG. 3 is a schematic diagram illustrating an exemplary electrical leadimplanted through the obturator foramen and disposed adjacent to apudendal nerve.

FIGS. 4A and 4B are views of an exemplary implant tool with a curvedneedle to implant an electrical stimulation lead adjacent to a pudendalnerve.

FIGS. 5A and 5B show views of an exemplary implant tool with a helicalneedle to implant an electrical lead adjacent to a pudendal nerve.

FIG. 6A shows the shape of an exemplary cannula on a needle of animplant tool.

FIG. 6B shows the shape of an exemplary cannula as a needle of animplant tool is being removed from the cannula.

FIGS. 7A-7C show exemplary electrical leads with tines to secure thelead within a patient.

FIG. 8 is a schematic diagram illustrating an exemplary implant toolcapable of providing test stimulation for determining correct leadplacement.

FIG. 9 is a functional block diagram illustrating various components ofan implant tool capable of providing test stimulation.

FIG. 10 is a flow chart illustrating a technique for implanting anelectrical lead adjacent to a pudendal nerve.

FIG. 11 is a flow chart illustrating a technique for performing teststimulation for determining the correct placement of an electrical lead.

FIG. 12 is a functional block diagram illustrating various components ofan implantable drug delivery device for providing neurostimulation.

FIG. 13 is a schematic diagram illustrating an exemplary leadlessstimulation module for stimulation of a nerve.

FIG. 14 is a schematic diagram illustrating implantation of a leadlessstimulation module through a cannula.

DETAILED DESCRIPTION

FIG. 1 is a schematic diagram illustrating an exemplary implant tool 24and a method of inserting the tool through an obturator foramen ofpelvis 10. As shown in FIG. 1, an anterior view of pelvis 10 includessacrum 14, inferior pubic ramus 16, ischial tuberosity 18, obturatorforamen 20 and acetabulum 22. Implant tool 24 includes housing 26, thumbrest 28 and needle 30. Implant tool 24 is used by a surgeon to locate anerve in pelvis 10 for the purpose of implanting an electrical lead orother medical device that stimulates the nerve. An introducer, in theform of needle 30 in the example of FIG. 1, is inserted throughobturator foramen 20 to access pelvic floor nerves of a patient. In thismanner, needle 30 supports transobturator access to the pelvic floornerves. Pelvic nerves may include sacral nerves, pudendal nerves, orbranches of pudendal nerves, and other pelvic nerves.

Implant tool 24 may be used to reach a wide variety of nerves which canbe accessed by the transobturator surgical procedure described herein.Some of these nerves include the pudendal nerve, various branches of thepudendal nerve, and the nerve of the clitoris, as well as other pelvicnerves. A transobturator method and implant tool 24 to implant anelectrical stimulation lead adjacent to the pudendal nerve will bedescribed herein as an example. Implant tool 24 may also be used toimplant a lead at other nerves within pelvis 10. In some cases, theshape of implant tool 24 may be modified to facilitate lead placementproximate a target nerve or nerves. Upon implantation of a distal end ofthe lead, a proximal end of the lead may be tunneled for connection toan implanted electrical neurostimulator or a lead extension coupled tothe neurostimulator. In some embodiments, a catheter may be tunneled todeliver drugs to a nerve from an implantable or external drug infusionpump. In other embodiments, implant tool 24 may implant a leadlessstimulator module so that a lead is not needed to be tunneled throughpatient 12. Needle 30, or any other needle described herein, may be anyobject that is introduced into or otherwise penetrates tissue of patient12.

The pudendal nerve originates from sacrum 14 and runs along the pelvicfloor before branching into other nerves that innervate organs and lowerextremities. Minimally invasive methods for implanting an electricallead adjacent the pudendal nerve are preferred, but involve risk incausing damage to surrounding healthy tissue, organs, or nerves. Inaddition, the use of imaging equipment to implant the lead may becumbersome or impractical in some cases. Advantageously, using thetransobturator method described in this disclosure, a physicianordinarily will be able to palpate anatomical landmarks, such as bone,muscle and ligament structures, to accurately locate the pudendal nerve.In this manner, implant tool 24 allows the physician to successfullylocate the pudendal nerve and effectively position a lead adjacent thenerve.

A transobturator procedure using implant tool 24 is preferably performedon a patient having normal anatomical soft tissue covering pelvis 10such as muscle, blood vessels, organs, and skin. FIG. 1 is forillustrative purposes and shows pelvis 10 without soft tissuesurrounding pelvis 10. The patient lies in a modified lithotomy positionto enable the physician to perform the procedure. The lithotomy positionis a position in which a patient is on her or his back with the hips andknees flexed and the thighs apart. This position is often used withfemale patients for vaginal examinations and childbirth. Local orgeneral anesthetics may be administered to minimize pain perceived bythe patient. The physician locates obturator foramen 20 by palpatinginferior pubic ramus 16 and ischial tuberosity 18 from inside of thevagina (not shown) for female patients, or from the inside of therectum, e.g., for female or male patients. With a finger locatingobturator foramen 20 from inside pelvis 10, the physician is able toidentify bone landmarks that indicate a path for insertion of needle 30.

Using the example of a female patient, needle 30 pierces skin in thepubic area between the vagina and an adjacent leg. The leg is attachedto acetabulum 22, so the leg limits entry angles of needle 30. Onceunderneath the skin, the physician follows the curve of needle 30 andadvances implant tool 24 in the direction of the arrow through obturatorforamen 20 to the approximate location of the pudendal nerve. In thecase of different nerves, i.e., other than the pudendal nerve, adifferent curve of needle 30 may aid in directing needle 30 to theappropriate nerve site.

The final placement of needle 30 may be partially determined by theischial spine (not shown), which is dorsal of the pudendal nerve.Ligaments near the pudendal nerve may also aid in guiding needle 30 tothe correct placement position adjacent to the pudendal nerve. Thesacrotuberous ligament provides a posterior stopping point for needle30, while the sacrospinous ligament creates an anterior border aroundthe pudendal nerve. The physician may use these ligaments to positionthe tip of needle 30 adjacent to the location of the pudendal nerve.

Handle 26 is shaped to allow a physician to hold it with one hand. Thumbrest 28 is also provided to the physician to support the simple handmotion of the transobturator procedure. Thumb rest 28 may be constructedof a soft rubber or plastic so that the physician's thumb does not slipduring the procedure. Other ergonomic features of handle 26 may beprovided as well. For example, the sides of handle 26 may follow thecontours of a hand or fingers. In addition, soft or rubber pads may beplaced where handle 26 contacts with the hand to provide a securegriping surface.

Implant tool 24 does not contain a lead when inserted into pelvis 10.Implant tool 24 does include a cannula (not shown) temporarily mountedon needle 30. The cannula is a hollow cylinder covering needle 30 and isof sufficient length to reach the pudendal nerve while a portion of thecannula remains outside of the patient. Once needle 30 is appropriatelypositioned near the pudendal nerve, the needle is removed from thecannula so that the cannula remains positioned adjacent to the pudendalnerve. A stylet and a lead are then inserted into the cannula whichserves as a lead introducer to guide the lead to the location adjacentthe pudendal nerve.

Once the lead is in place, the stylet and cannula are removed and thelead is left in place to provide electrical stimulation to the pudendalnerve. The lead is secured in place with tines, or other anchoringstructure, on the lead that are embedded within tissue of the pelvis.For example, tines may be disposed within an obturator muscle coveringobturator foramen 20. Tines on the lead may also be attached to othersurrounding tissue. In other embodiments, the cannula may reside withinneedle 30 before being deployed into pelvis 10.

After the lead is placed near the pudendal nerve, it is tunneled throughthe patient to a trial stimulator or chronic stimulator that provideselectrical stimulation therapy to the pudendal nerve through theimplanted lead. The lead may exit the patient's skin when attached to anexternal trial stimulator to evaluate stimulation therapy. In someembodiments, a perctuaneous lead extension couples the lead to theexternal trial stimulator. In this manner, the lead may be used with animplantable electrical neurostimulator if desired. The external trialstimulator may be located on the patient to avoid implantation in thecase where electrical stimulation therapy is not effective. The lead mayalso be tunneled to a subcutaneous area where a chronic stimulator isimplanted.

The location at which the chronic stimulator is implanted may varyaccording to the health, condition or anatomy of the patient. Examplesof possible locations for a chronic stimulator may include the lowerback, buttocks, abdomen, or thigh. In each case, electrical stimulationis delivered through the electrodes of the lead implanted adjacent tothe pudendal nerve via the transobturator technique described in thisdisclosure. The stimulator is programmed to deliver electricalstimulation therapy appropriate for treatment of urinary incontinence,sexual dysfunction, pelvic pain or other pelvic floor disorders.

In some embodiments, implant tool 24 may be completely disposable toeliminate possible contamination between different patients. In otherembodiments, one or more components of implant tool 24 may be reusableto reduce equipment costs. For example, handle 26 may be reusable as itdoes not come into contact with the patient. Handle 26 may besterilizable in the event that biological tissues come into contact withthe handle. Needle 30 may be detachable and disposable. Alternatively,needle 30 may be autoclaved or chemically sterilized for use inimplanting a lead into a different patient.

Introduction of a needle and cannula have been described above. Inalternative embodiments, however, a hollow needle may be used. In thiscase, it may be possible to eliminate use of a cannula. Instead, astylet and lead may be introduced via an inner lumen of the needle thatextends through the obturator foramen. Accordingly, the inner lumen ofthe hollow needle may be sized to accommodate the lead, and the styletwithin the inner lumen of the lead. In this manner, it is not necessaryto place the needle, place the cannula, withdraw the needle, and thenplace the stylet and lead. Instead, the stylet and lead may beintroduced via the needle, reducing the number of steps necessary forimplantation of the lead. In many embodiments, however, it will bedesirable to use a needle and cannula.

FIG. 2 is a schematic diagram illustrating an exemplary implant toolinserted through an obturator foramen to reach a pudendal nerve. In theexample of FIG. 2, pelvis 10 includes sacrum 14, inferior pubic ramus16, ischial tuberosity 18, obturator foramen 20, and ischial spine 12.FIG. 2 shows an interior view of pelvis 10. Vertebrae 32 are attached tosacrum 14 and protect the spinal cord (not shown) as it travels from thebrain to pelvis 10. S2 nerve 34, S3 nerve 36, and S4 nerve 38 emanatefrom the spinal cord out from sacrum 14. Nerves 34, 36, and 38 combineposterior of ischial spine 12 to form pudendal nerve 40. Pudendal nerve40 branches into perineal branch 42 and anal branch 44. Needle 30 isshown inserted through obturator foramen 20 into the interior of pelvis10 and adjacent to pudendal nerve 40.

Pudendal nerve 40 may be difficult to access using surgical techniquesas it is located deep within tissues of pelvis 10. Pudendal nerve 40 issurrounded by other nerves and important tissues, so accurate guidanceof needle 30 may be difficult without internal guides when insertingneedle 30. To aid in insertion, the physician may insert one or morefingers into a vagina or rectum of the patient (not shown) to palpatestructures of pelvis 10. Through trans-vaginal or trans-rectalpalpations, the physician may locate ischial tuberosity 18 as theinferior boundary of obturator foramen 20. The physician may alsopalpate ischial spine 12, which the physician may use to aim needle 30through obturator foramen 20. The procedure may be performedtrans-vaginally in a female patient, or in a male or female patient bypalpating the bone landmarks through the rectum.

Inserting needle 30 into pelvis 10 with a transobturator procedure maybe beneficial over other methods to reach pudendal nerve 40. Since thereare no nerves passing over obturator foramen 20, it is unlikely thatneedle 30 would disturb another nerve near pudendal nerve 40. Inaddition, the physician needs only a simple hand motion to insert needle30 adjacent to pudendal nerve 40. Anatomical structures may also aid inguiding needle 30 to the correct location. As mentioned previously, thesacrotuberous ligament (not shown) provides a posterior stopping pointfor needle 30 inferior to pudendal nerve 40. If the physician strikesthe sacrotuberous ligament, needle 30 may be retracted slightly for goodplacement near pudendal nerve 40. The sacrospinous ligament (not shown)creates an anterior border around pudendal nerve 40. The physician mayuse these two ligaments to locate pudendal nerve 40 between theligaments.

While the shape of needle 30 simplifies pudendal nerve isolation, othertechniques may be useful in fine adjustment of the needle position.Instead of using strictly anatomical landmarks to position needle 30adjacent pudendal nerve 40, imaging techniques such as fluoroscopy maybe used in some embodiments. The physician also may rely on tactilefeedback to guide placement, e.g., from needle 30 contacting ligaments,muscle bones or other structure. Alternatively, or additionally, implanttool 24 may be attached to or integrated with a test stimulator (notshown in FIG. 2) that produces electrical stimulation to verify accurateneedle placement relative to the pudendal nerve. For example, as will bedescribed in greater detail, the test stimulator may include anelectrical stimulation pulse generator electrically coupled to needle 30via an electrical conductor and electrically coupled to a groundelectrode pad, which may be attached to an exterior location of thepatient.

Needle 30 may include an electrode near the tip of the needle to deliverelectrical pulses to pudendal nerve 40. Preferably, the majority ofneedle 30 is electrically insulated from the electrode so thatstimulation energy can be generally confined to the needle tip. Hence,the electrode 30 may be provided by an electrically conductive needle30, or a dedicated electrode (shown in FIGS. 4A and 4B) may be formed ator near a distal tip of needle 30, e.g., by deposition, crimping,welding, or other fabrication techniques. Upon delivery of stimulationenergy to the electrode, the physician may identify muscle movementassociated with appropriate pudendal nerve stimulation to correctlyplace needle 30. Alternatively, electromyography may be performed withthe test stimulator or another device to observe a sphincter compoundmuscle action potential (CMAP) which aids in correct needle 30placement. In either case, the test stimulator aids the physician inpositioning needle 30 relative to the pudendal nerve.

A cannula (not shown in FIG. 2) may be located around needle 30, andutilized when implanting a lead. Needle 30 resides within an inner lumendefined by the cannula. The distal tip of needle 30 protrudes from adistal end of the cannula to provide a sharp needle point forpenetration of tissue during the transobturator approach to the pudendalnerve 40. In other embodiments, needle 30 may comprise a dull or bluntpoint to limit tissue damage from contact with a sharp point. Onceneedle 30 is positioned correctly, the needle is removed from thecannula such that the cannula remains in place and the distal end of thecannula remains adjacent to pudendal nerve 40. The cannula provides anentry into the patient for implantation of the stimulation lead withinpelvis 10. The cannula may be flexible and orient itself to followpudendal nerve 40. The cannula may also be moved slightly without needle30 for fine adjustment of the placement location. In some cases, thecannula may be slightly malleable so that the physician may customizethe shape of the cannula to target a desired nerve site.

In other embodiments, needle 30 may be used to access other nerves inpelvis 10. For example, needle 30 may be inserted though obturatorforamen 20 to reach the nerve of the clitoris located near inferiorpubic ramus 16. Needle 30 may also be used to implant a lead or leadlesselectrical nerve stimulation module near perineal branch 42 or analbranch 44 of pudendal nerve 40. Needle 30 or the cannula may be shapedslightly differently to access nerves other than pudendal nerve 40.

FIG. 3 is a schematic diagram illustrating an exemplary electrical lead46 implanted through an obturator foramen and disposed adjacent to apudendal nerve. As shown in FIG. 3, lead 46 is implanted adjacentpudendal nerve 40 in pelvis 10. A stylet (not shown in FIG. 3) is usedto guide lead 46 down the cannula (not shown in FIG. 3) and adjacent topudendal nerve 40, e.g., for delivery of stimulation energy to alleviateurinary incontinence, fecal incontinence or sexual dysfunction. Thecannula serves as a lead introducer. In some embodiments, teststimulation may be delivered from an external stimulator, or a teststimulator that is coupled to or integrated with tool 24, to ensureelectrodes at the distal end of lead 46 are located in a correctposition relative to pudendal nerve 40. If the location of lead 46 isincorrect, the cannula may be adjusted, either longitudinally orrotationally, to provide better electrical contact between theelectrodes carried by lead 46 and pudendal nerve 40.

The cannula may be removed from lead 46 when the lead 46 provides goodcapture of pudendal lead 40. Lead 46 is disposed within a tunnel createdby needle 30 and the cannula. Lead 46 may include tines or otherstructure to anchor the lead within tissue of pelvis 10. Thetransobturator procedure for lead implantation provides secure anchoringtissue for the tines of lead 46. For example, tines may be securedwithin the obturator muscle covering obturator foramen 20. Anchoringlead 46 within the obturator muscle may limit the amount of movement oflead 46 away from pudendal nerve 40. In some embodiments, other anchormechanisms may be needed to secure lead 46 within patient 12. Someexample anchor mechanisms may include screws, porous structures thatallow tissue in-growth, or sutures.

Lead 46 is tunneled through tissue and coupled to a trial or chronicelectrical stimulator (not shown in FIG. 3). In some embodiments, lead46 may be coupled to a trial stimulator located external to the patient.A trial stimulator permits the physician and the patient to evaluatestimulation efficacy before implanting a stimulator. If stimulationtherapy is unsuccessful, the trial stimulator is simply disconnectedfrom lead 46 and the lead is removed from the patient. In otherembodiments, lead 46 is tunneled subcutaneously to a location where achronic stimulator is implanted beneath the skin. The chronic stimulatormay provide months or years of stimulation therapy with the use of lead46, so implantation of a chronic stimulator may be preferred. Lead 46may be used by both a trial stimulator if therapy is successful, or lead46 may be coupled to a chronic stimulator without using a trialstimulator for an evaluation period. In the case of trial stimulation, apercutaneous extension may be coupled to a chronically implanted lead topreserve sterile integrity of the chronically implanted lead.

An implanted chronic stimulator may be located at a variety of locationswithin the patient. Preferably, the implanted stimulator may be locatednear lead 46 and in a location that does not interfere with patientactivity. For example, the stimulator may be located in the abdomen,buttocks, lower back, or thigh. In any location, lead 46 may be ofsufficient length to reach both pudendal nerve 40 and the stimulator,either directly or via a lead extension coupled to the implantedstimulator.

In other embodiments, the distal end of lead 46 may be positionedadjacent other pelvic floor nerves. For example, lead 46 may be insertedinto a cannula with a distal end positioned adjacent the nerve of theclitoris, e.g., for delivery of electrical neurostimulation to alleviatesymptoms of sexual dysfunction or incontinence. In any nerve location,lead 46 may be implanted through obturator foramen 20. In someembodiments, however, lead 46 may not be tunneled through obturatorforamen 20. In particular, lead 46 alternatively may be implantedthrough the obturator foramen 20 as described, but the proximal end ofthe lead may then be tunneled through another location of pelvis 10. Inthis case, the initial use of the transobturator approach ensuresaccurate lead placement relative to the pudendal nerve or other nerves,but the lead is then tunneled using a different path to reach theimplanted stimulator. This lead 46 tunneling may be beneficial to reachcertain stimulators or avoid a location of concern related to the healthof the patient.

FIGS. 4A and 4B show views of exemplary implant tool 24 with a curvedneedle 30 to implant an electrical lead adjacent to a pudendal nerve. Asshown in the side view of FIG. 4A, implant tool 24 includes handle 26,neck 48, needle 30, electrode 49 and tip 50. Handle 26 is generallyrectangular in shape and has curved edges. Neck 48 securely attachesneedle 30 to handle 26. Neck 48 may provide an attachment mechanism toenable needle 30 to be removed from neck 48. Detachment of needle 30 maybe necessary if needle 30 is to be disposable or sterilizable separatefrom handle 26. Alternatively, neck 48 may be permanently attached toneedle 30 and neck 48 is removable from handle 26.

Needle 30 is solid and curved at bend point 51 to facilitate entrythrough obturator foramen 20 and enable access to pudendal nerve 40. Tip50 is used to pierce tissue and create a tunnel through pelvis 10. Tip50 may be shaped similar to a wedge, cone, pyramid, or any other shapethat includes decreased surface area at the distal end of needle 30 todefine a sharp point. Needle 30 may be formed from a metal alloy such asstainless steel, aluminum or nitinol. An electrically conductiveelectrode 49 may be located near or on tip 50 for test stimulationduring placement of needle 30. Electrode 49 may be cylindrical,circular, or rectangular in shape. Alternatively, the entire needle 30may be electrically conductive. In this case, the majority of needle 30may be covered with an electrically insulative coating or sleeve.Alternatively, a cannula placed over needle 30 may be electricallyinsulative.

Hence, the electrode may be formed at a distal end of needle 30 andcoupled to an electrical conductor within the needle, or the entireneedle may be electrically conductive, in which case an insulativecoating, sleeve or cannula defines the size and length of the electrodeat the distal end of needle 30. In each case, the insulative coating,sleeve or cannula limits stimulation energy to a small electrode area atthe distal end of needle 30. In some other embodiments, an insulativecoating, sleeve or cannula may define one or more window-like aperturesthat expose selected portions of the needle 30 to define one or moreelectrode regions either at the distal tip 50 or displaced some distanceform the distal tip.

In some embodiments, needle 30 is hollow and open at tip 50. A hollowneedle 30 may allow the inclusion of a visualization scope to enable thephysician to view interior regions of pelvis 10 at tip 50 or permit theflow of a fluid to the tissue to lubricate or anesthetize thesurrounding tissue or reduce tissue damage. In alternative embodiments,a hollow needle 30 may enable a lead to be inserted through the needleinstead of through a cannula left within pelvis 10. Needle 30 mayalternatively be capable of directly injecting a leadless electricalstimulation module that provides leadless electrical stimulation using aunitary, integrated stimulation module carrying one or more electrodes,stimulation pulse generation circuitry, and optionally telemetrycircuitry.

Needle 30 may vary in length. Different sized patients may requiredifferent sizes of needle 30. In general, the length of needle 30 may bein a range of approximately 5 cm to 50 cm. More specifically, the lengthof needle 30 may be in a range of approximately 15 cm to 25 cm. In somecases, the length of needle 30 may be approximated by the height of thepatient. In other cases, one length of needle 30 may be appropriate forany sized patient. Generally, the diameter of needle 30 may be in arange of approximately 1.0 mm to 5.0 mm. Needle may have a radius ofcurvature about bend point 51 in a range of approximately 2 cm to 20 cm,and more preferably approximately 5 cm to 15 cm, to permit ease oftransobturator insertion to the desired nerve site.

In some embodiments, handle 26 may be formed in a cylindrical,spherical, or other ergonomic shape designed to be held by one hand. Agenerally cylindrical handle 26 shape may provide the most flexibilityto a physician using implant tool 24. In other words, the physician mayhold handle 26 at any circumference to direct needle 30 to any location.A cylindrical handle shape may also allow the physician to easilymanipulate implant tool 24 when attempting to position needle 30 nearpudendal nerve 40. For example, the physician may readily move handle 26longitudinally and rotationally, as needed, during the transobturatorprocess.

Handle 26 may generally be in a range of approximately 10 cm to 30 cm inlength, 1 cm to 10 centimeter in width, and 0.5 cm to 5 cm in depth.Preferably, handle 26 may be in a range of approximately 10 cm to 15 cmin length, 2 cm to 4 cm in width, and 1 cm to 3 cm in depth. Handle 26may be provided in different sizes to accommodate different sized handsof varying physicians. In addition, handle 26 may be made to accommodateuse in a right or left hand, either as ambidextrous or separate models.

Handle 26 may be constructed of an injection moldable plastic such aspolystyrene, polypropylene, polycarbonate, or any other polymer. In someembodiments, handle 26 may be constructed of a metal alloy includingstainless steel or aluminum or a composite material. The material usedto construct handle 26 may be dependent on the intended life of implanttool 24. For example, a disposable handle 26 may require an inexpensiveplastic material, while a reusable handle 26 may require a more durablemetal material. In addition to these materials, ergonomic rubber orsimilar material may be added to handle 26 to increase ease of use ofimplant tool 24.

Needle 30 may be constructed of a metal alloy with a strength andstiffness great enough to resist substantial bending upon insertionwithin pelvis 10. As mentioned above, such metals may include stainlesssteel, aluminum or nitinol. In some embodiments, a plastic material maybe used to construct needle 30. If a plastic material is used, anelectrical conductor may be provided within needle 30 for conduction ofstimulation energy to an electrode formed at or adjacent to distal tip50 of the needle. In some cases, needle 30 may be shaped by a physician.

FIG. 4B shows a top view of implant tool 24. Thumb rest 28 is providedon handle 26 to facilitate manipulation by a physician. Thumb rest 28may be constructed of a soft rubber or other elastomeric material toprovide comfort and friction between the thumb of a physician and handle26. As shown in FIGS. 4A and 4B, needle 30 is curved in only one plane.In some embodiments, needle 30 may be curved outside of one plane tofacilitate insertion of needle 30 into pelvis 10. For example, needle 30may include a complex bend, such as a partial or full helical bend.

FIGS. 5A and 5B show views of exemplary implant tool 52 with needle 58having a helical bend to implant an electrical lead adjacent to apudendal nerve. As shown in FIG. 5A, implant tool 52 includes handle 54,neck 56, needle 58, electrode 59, and tip 60. Similar to handle 26,handle 54 is substantially rectangular in shape and has curved edges.Neck 56 securely attaches needle 58 to handle 54. In the example ofFIGS. 5A and 5B, needle 58 is solid and curved to form a helical shapeto facilitate entry through obturator foramen 20 and enable access topudendal nerve 40.

Needle 58 is inserted into the patient and twisted about a long axis ofhandle 54 to pass through obturator foramen 20. The helix of needle 50is shaped to facilitate accurate placement of needle 58 adjacentpudendal nerve 40. Tip 60 is used to pierce tissue and create a tunnelthrough pelvis 10. As in the example of FIGS. 4A and 4B, tip 60 may beshaped similar to a wedge, cone, pyramid, or any other shape thatincludes decreased surface area at the end of needle 58. An electricallyconductive electrode 59 may be formed near or on tip 60, e.g., by any ofthe techniques described with respect to FIGS. 4A and 4B, for teststimulation during placement of needle 58. Electrode 59 may becylindrical, circular, or rectangular in shape. Similar to implant tool24, a cannula may also be used when implanting a lead. In someembodiments, needle 58 may be hollow and open at tip 60, e.g., to permitintroduction of a visualization scope or a fluid into the interior ofpelvis 10.

Helical needle 58 may vary in length, e.g., according to different sizepatients. In general, the length of needle 58 may be in a range ofapproximately 5 cm to 50 cm. More preferably, the length of needle 58may be in a range of approximately 20 cm to 30 cm. The radius of thehelix of needle 58 may be dependent on the individual patient. Ingeneral, the radius of curvature of needle 58 may be in a range ofapproximately 1 cm to 15 cm. More preferably, the radius of curvature ofneedle 58 may be in a range of approximately 2 cm to 10 cm. In addition,needle 58 may include more or less rotations of the helix. In theexample of FIG. 5A, needle 58 includes a helix of approximately 360degrees. Needle 58 may include as little as 90 degrees of a helix or asmuch as 720 degrees of a helix. Generally, the diameter of needle 58 maybe in a range of approximately 1.0 mm to 5.0 mm.

In some embodiments, handle 54 may be cylindrical, spherical, or anotherergonomic shape designed to be held by one hand. A cylindrical handle 54shape may provide the most flexibility to a physician using implant tool52. In other words, the physician may hold handle 52 at anycircumference to direct needle 58 to any location. A cylindrical handleshape may also allow the physician to easily rotate and manipulateimplant tool 52 when attempting to position needle 58 near pudendalnerve 40.

Similar to handle 26, handle 54 may generally be in a range ofapproximately 10 cm to 30 cm in length, 1 cm to 10 centimeter in width,and 0.5 cm to 5 cm in depth. Preferably, handle 26 may be in a range ofapproximately 10 cm to 15 cm in length, 2 cm to 4 cm in width, and 1 cmto 3 cm in depth. Handle 54 may be provided in different sizes toaccommodate different sized hands of varying physicians.

Handle 54 may be constructed of materials similar to those describedwith reference to FIGS. 4A and 4B. Also, needle 58 may be constructed ofa metal alloy with a strength and stiffness great enough to resistbending upon insertion within pelvis 10, as described with reference toneedle 30. Such metals may include stainless steel, aluminum, ornitinol. In some embodiments, however, a plastic material may be used toconstruct needle 58, which may require an electrical conductor fordelivery of stimulation energy to an electrode placed at or near distaltip 60.

FIG. 5B shows a top view of implant tool 52. Thumb rest 62 is providedon handle 54 to facilitate rotation and manipulation of implant tool 52by a physician, and may be constructed as described with reference toFIGS. 4A and 4B. In operation, a physician penetrates obturator foramenwith distal tip 60 of needle 58 and rotates handle 54 to move needle 30into the interior of the pelvis such that distal tip 60 is placedadjacent a desired nerve site, such as the pudendal nerve.

FIG. 6A shows the shape of an exemplary cannula 64 mounted over needle30 of an implant too 24. Needle 30 is within the inner lumen of cannula64. Cannula 64 covers the outside of needle 30 before needle 30 isimplanted within the patient. Cannula 64 is of sufficient length thatthe cannula may reach pudendal nerve 40 and completely exit the patientpercutaneously, and is of sufficient diameter to allow a lead to slidewithin the inner lumen of cannula.

Cannula 64 may serve simply as a lead introducer, once needle 30 isremoved from the patient. Alternatively, cannula 64 may perform the dualrole of lead introducer and electrical insulator. As an electricalinsulator, cannula 64 electrically insulates most of needle 30, but maybe sized to permit a distal tip of the needle to be exposed. Forembodiments in which needle 30 is electrically conductive, the distaltip of the needle may form an electrode region for delivery ofstimulation energy on a test basis, while the remainder of the needle isinsulated so that the stimulation energy is isolated to the electroderegion.

Cannula 64 may be somewhat flexible to permit it to assume the shape ofneedle 30. As cannula 64 is placed over needle 30, for example, thecannula assumes a first shape, i.e., the shape of needle 30. The radiusof curvature, R_(N), of needle 30 may vary with regard to the patient.In general, as described previously, R_(N) may be in a range ofapproximately 2 cm to 20 cm. More preferably, R_(N) may be in a range ofapproximately 5 cm to 15 cm. In any case, the radius of curvature isused to reach pudendal nerve 40.

Cannula 64 is constructed of a flexible material with a shape memory inthe material. The normal shape of cannula 64 may not be the shape ofneedle 30. In order for cannula 64 to aid in lead implantation, thecannula material may change shape once needle 30 is removed. Cannula 64also may be electrically insulative. Cannula 64 may be constructed of aplastic capable of being thermoset, or heated to a certain shape. Such apolymer may include ethylene tetrafluoroethylene (ETFE). ETFE may alsoprovide some torsional rigidity to aid in cannula 64 movement withinpelvis 10. Other materials such as nitinol may be used to constructcannula 64 as well. Nitinol may provide an additional benefit in that itmay be more readily visualized during fluoroscopy. Fluoroscopy may beused to aid in placement of needle 30 adjacent to pudendal nerve 40. Inaddition to the shape memory material of cannula 64, a coating may alsobe applied to the cannula. For example, a parylene or oxide film coatingmay be applied to cannula 64 in order to electrically insulate thecannula. Also, addition of a lubricating film or coating, such as PTFE,to the outer surface of cannula 64 may be desirable to facilitateinsertion.

FIG. 6B shows the shape of exemplary cannula 64 as needle 30 of animplant tool is being removed from the cannula. As needle 30 is removedfrom cannula 64, the cannula changes conformation to a second shape. Thesecond shape aids in guiding the distal tip of a lead along the side ofpudendal nerve 40. The second shape is formed in the material of cannula64, and assumes a radius of curvature R_(C). R_(C) may vary due topatient anatomy or nerve targeted to be stimulated. In general, R_(C) isin a range of approximately 1 cm to 20 cm. More preferably, R_(C) is ina range of approximately 2 cm to 10 cm.

As needle 30 is completely removed from cannula 64, the cannula remainsin the second shape. A stylet and lead is then inserted into cannula 64.In particular, the stylet is inserted into an inner lumen defined by thelead, and the combined lead and stylet are then inserted into the innerlumen of cannula 64. Upon insertion into cannula 64, the lead isdeflected to a location adjacent pudendal nerve 40, such as towardischial spine 12. While cannula 64 is flexible, the physician may beable to slightly move cannula 64 while implanting the lead to theappropriate location. Once the lead is implanted, cannula 64 may beremoved and disposed, leaving the stylet and lead in place within thepelvis of the patient. In some cases, cannula may be sterilized andreused in another procedure.

FIGS. 7A-7C show exemplary electrical leads with tines to secure thelead within a patient. As shown in FIG. 7A, lead 46 includes housing 66,tines 68A, 68B, 68C, and 68D (collectively tines 68), and electrodes70A, 70B, 70C, and 70D (collectively electrodes 70). Lead 46 may be astandard lead that includes all four tines 68 close to electrodes 70.Implanting lead 46 may be beneficial due to tines 68 being anchoredclose to electrodes 70. A smaller distance between tines 68 andelectrodes 70 may allow less movement of electrodes 70 with respect toadjacent pudendal nerve 40.

Electrodes 70 are more effective in delivering electrical stimulationwhen the electrodes are located close to pudendal nerve 40. Ifelectrodes 70 migrate away from pudendal nerve 40, efficacy ofstimulation therapy may decrease. Therefore, tines 68 located close toelectrodes 70 may be beneficial to therapy efficacy. However, tines 68may not be capable of anchoring into a solid tissue if they are locatedtoo close to electrodes 70. Since an obturator muscle may be somedistance from pudendal nerve 40, tines 68 may only be able to anchor inless stable tissue.

FIG. 7B illustrates a lead 72 which includes housing 78, tines 74A, 74B,74C, and 74D (collectively tines 74), and electrodes 76A, 76B, 76C, and76D (collectively electrodes 76). Tines 74 are located a distance D awayfrom the most proximal electrodes 76. Lead 72 may be capable ofanchoring tines 74 in an obturator muscle while enabling electrodes 76to reach further away from the anchoring point to pudendal nerve 40.Distance D may be generally in a range of approximately 0.5 cm to 10 cm,and more preferably 1 cm to 4 cm. While lead 72 may provide a moresecure anchoring point, electrodes 76 may be free to migrate to anunacceptable distance away from pudendal nerve 40.

FIG. 7C illustrates a lead 80 which includes housing 82, tines 84A, 84B,84C, 84D, 84E, 84F, 84G, and 84H (collectively tines 84), and electrodes86A, 86B, 86C, and 86D (collectively electrodes 86). The increasednumber of tines 84 located on lead 80 may provide secure anchoring in anobturator muscle and soft tissue closer to pudendal nerve 40. Lead 80may be capable of providing better anchoring points and eliminatingmigration of electrodes 86 with respect to pudendal nerve 40. However,removal of lead 80 may injure a greater volume of tissue. Therefore,lead 80 may be more appropriate for patients with more active lifestyleswhere lead migration may be a problem.

In any of leads 46, 72, and 80, any number of electrodes or tines may beimplemented. Although leads 46, 72, 80 each include four electrodes, theleads may include one, two, four, eight or more electrodes. In addition,any number of tines may be used. Also, in some cases, it may bedesirable to deploy two or more leads, each carrying one or moreelectrodes. Any of these configurations may be possible and desirablewhen implanting a lead to stimulation pudendal nerve 40 via thetransobturator approach described in this disclosure. Other exemplaryleads for urinary incontinence applications include the leads identifiedby model no. 3080, 3092, 3093, 3886, 3889 and 3966, and manufactured byMedtronic, Inc., of Minneapolis, Minn. Such leads and the leadsdescribed herein may be used in conjunction with the Model 3023InterStim® implantable stimulator, also manufactured by Medtronic, Inc.

FIG. 8 is a schematic diagram illustrating exemplary implant tool 88capable of providing test stimulation for determining correct leadplacement. As shown in FIG. 8, implant tool 88 is similar to implanttool 24 of FIG. 1. Implant tool 88 includes handle 90, neck 92, needle94, switch 96, connector 102, cable 100, and ground electrode 98.Implant tool 88 may be used to implant a lead near pudendal nerve 40using a transobturator approach, as described herein, and providepreliminary test stimulation without the need to implant a lead orcouple needle 94 to an additional device. Handle 90 is also a housingwhich contains electronics and a power source necessary to provide teststimulation pulses when determining the correct placement of needle 94.

Needle 94 is curved similar to needle 30. Once needle 94 is correctlyplaced within pelvis 10, implant tool 88 may provide test stimulationpulses to specifically locate the best location to place a lead. Thetest stimulation pulses may be delivered via an electrode region at ornear the distal tip of needle 94. Again, a dedicated electrode may bepositioned at the distal tip, or the entire needle 94 may beelectrically conductive but insulated to isolate stimulation to a regionat or near the distal tip. Ground electrode 98 is placed on an externalsurface of the patient and forms another electrode so that unipolarstimulation can be delivered by the electrode carried by needle 94. Anappropriate location for placement of ground electrode 98 may be thesmall of the back or the buttocks. Cable 100 is also connected to handle90 with connector 102. The electrode at or near the distal end of theneedle 94 delivers unipolar stimulation to the region of pudendal nerve40. When the physician desires to analyze the location of the distal tipof needle 94 for proximity to the pudendal nerve 40, switch 96 is slidto the “ON” position to deliver test stimulation pulses. Switch 96 ismoved to the “OFF” position once test stimulation is no longer needed.

Implant tool 88 may be programmed through a user interface located onthe side of handle 90. Parameters such as voltage amplitude, currentamplitude, pulse width, pulse frequency, duty cycle or other stimulationparameters may be adjusted before or during test stimulation.Alternatively, the parameters of the stimulation energy output fromimplant tool 88 may be fixed, or include a series of pulses withdifferent parameters according to a predetermined sequence. In otherembodiments, parameters may be adjusted by connecting a programmer tohandle 90 through a wired connection or wireless telemetry.

As a further alternative, handle 90 may simply provide an electricalterminal for connection to an external test stimulator, and therebyserve as an electrical conduit between the test stimulator and needle94. In addition, implant tool 88 may be able to store stimulationinformation and transfer the information to another device. Inparticular, implant tool 88 may include the capability to storestimulation information to memory to aid a physician in efficientlyproviding test stimulation.

In some embodiments, implant tool 88 may be capable of deliveringbipolar test stimulation. Needle 94 may include more than one electrodeto enable anode and cathode configurations for delivery of bipolarstimulation at or near the distal tip of the needle. In this case,ground electrode 98 would not be necessary. Bipolar stimulation mayprovide more accurate test stimulation of pudendal nerve 40, but may notreadily allow for CMAP observation during placement of needle 94.

A cannula as described previously may be used with implant tool 88.Advantages of implant tool 88, in embodiments in which a stimulator isintegrated with the tool, include fewer devices for the physician tooperate and shorter implantation time of a lead to pudendal nerve 40. Inother embodiments, implant tool 88 may include a channel though handle90 and needle 94 to facilitate lead insertion directly though implanttool 88. Although needle 94 is shown as a simple needle, e.g., with acurve in one plane, needle 94 may be similar to helical needle 58.

Needle 94 may be disposable or sterilizable, similar to needle 30.Ground electrode 98 also may be disposable or sterilizable. Connector102 and cable 100 may be disposable if permanently attached to adisposable ground electrode 98 or reusable if cable 100 temporarilyattaches, such as with a clamp, to ground electrode 98.

FIG. 9 is a functional block diagram illustrating various components ofimplant tool 88 capable of providing test stimulation. Implant tool 88includes handle 90, or housing 90. Components within housing 90 includeprocessor 104, memory 106, pulse generator 108, user interface 110, andpower source 112. Needle 94 includes at least one electrode and cable100 is connected to ground pad 98. Memory 106 stores instructions forexecution by processor 104, stimulation parameters and, optionally,information related to the use of needle 94. Memory 106 may includeseparate memories for storing instructions, stimulation parameter sets,and stimulation information, or a common memory.

Pulse generator 108 is programmed with stimulation pulse parametersappropriate for delivery of test stimulation in the form of stimulationpulses delivered continuously or in selected bursts. Pulse generator 108may be substantially similar to a trial or chronic stimulator used totreat the patient. The physician may set test parameters for pulsegenerator 108 to reproduce.

Processor 104 controls pulse generator 108 to deliver electricalstimulation therapy. Based on stimulation parameters programmed by thephysician through user interface 110, processor 104 instructsappropriate stimulation by pulse generator 108. Information may also bereceived from user interface 110 at any time during operation, in whichcase a change in stimulation parameters may immediately occur. Userinterface 100 may be accessed directly on handle 90 as a set ofswitches, dials, buttons, or other input media, or accessed via anexternal programmer that transmits information to tool 88 by wired orwireless telemetry. In some embodiments, wireless telemetry in implanttool 88 may be accomplished by radio frequency (RF) communication orproximal inductive interaction of implant tool 88 with anotherprogramming device via a telemetry interface (not shown). Processor 104may control the telemetry interface to exchange information with theprogramming device. Processor 104 may transmit operational informationand other information to the programming device via the telemetryinterface.

Processor 104 determines any pulse parameter adjustments based on thereceived information, and loads the adjustments into memory 106 for useduring delivery of stimulation. As mentioned above, user interface 110may include a series of switches, dials, or buttons for changingstimulation parameters. User interface 110 also may include an LED orLCD display indicating the values of current stimulation parameters,battery life, and any operational information. Alternatively, userinterface 110 may be a touch screen for modification of stimulationparameters. User interface 110 may be disabled by the physician duringtest stimulation to eliminate the chance of unsafe stimulationmodifications during handling of handle 90.

Power source 112 delivers operating power to the components of implanttool 88. Power source 112 may include a battery and a power generationcircuit to produce the operating power. In some embodiments, the batterymay be rechargeable to allow extended operation Recharging may beaccomplished through proximal inductive interaction between an externalcharger and an inductive charging coil within stimulator 12. In otherembodiments, power source 112 may recharge though an alternating currentadapter charger. Alternatively, power source 112 may directly utilizeexternal power from an alternating current source, e.g., withappropriate isolation and ground fault interruption circuitry.

FIG. 10 is a flow chart illustrating a technique for implanting anelectrical lead adjacent to a pudendal nerve. The transobturatortechnique, or procedure, is described to provide a physician with asimple, effective, and repeatable method for accessing the pudendalnerve deep in pelvis 10 of a patient. Using implant tool 24 (implanttool 88 may also be used), in the example case of a female patient, aphysician places needle 30 on skin of the pubic area between a vaginaand interior thigh of the adjacent leg. Once the physician enters thevagina (or the rectum) with one or more fingers to palpate the ischialtuberosity 18 or ischial spine 12 trans-vaginally (or trans-rectally),the physician pierces the skin and inserts needle 30 lateral to thepubic symphysis of pelvis 10 toward obturator foramen 20 (114). Needle30 is then tunneled through obturator foramen 20 by using a forward andup motion following the curve of needle 30 (116).

The goal is to capture pudendal nerve 40 by placing the tip of needle 30adjacent to the pudendal nerve (118). A physician may use one or both ofthe following techniques to correctly capture pudendal nerve 40. Thephysician may use tactile feedback from needle 30 striking ligamentssurrounding pudendal nerve 40 (120). For example, needle 30 may beretracted slightly if the needle contacts the sacrotuberous ligamentposterior to pudendal nerve 40. In addition, the sacrospinous ligamentmay be used to locate an anterior edge of pudendal nerve 40 position. Inaddition to or alternatively, the physician may perform test stimulationto correctly position and capture pudendal nerve 40 (122). As describedabove, a separate test stimulation device or implant tool 88 may be usedto deliver test pulses to pudendal nerve 40. The physician may observemuscle contractions or a CMAP of the sphincter to identify the locationof needle 30 or needle 94 where stimulation is most effective. If theplacement of needle 30 is not successful (124), the physician mayattempt to capture pudendal nerve 40 once more (118). If the placementof needle 30 is successful, the physician may continue to implant thelead.

Once the placement of needle 30 is correct, the physician removes needle30 from cannula 64 (126). Lead 46 (or any other lead described herein)is inserted into cannula 64 with a stylet to aid in navigating curves ofthe cannula (128). Once lead 46 is correctly placed adjacent pudendalnerve 40, the physician removes the stylet from lead 46 (130). Thephysician then removes cannula 64 from lead 46 to finish theimplantation of the lead adjacent to pudendal nerve 40 (132).

In some embodiments, implant tool 52 may be used instead of implanttools 24 or 88. The procedure of FIG. 10 remains similar, with analternative method in inserting needle 58. Implant tool 52 requires atwisting motion to tunnel helical needle 58 through obturator foramen 20and reach pudendal nerve 40. In either case, the associated implant toolmay aid in lead implantation at the pudendal nerve.

In other embodiments, the transobturator procedure of FIG. 10 may besimilar when implanting a lead near a different nerve of the pelvicfloor. For example, the procedure may be substantially similar whenaccessing the nerve of the clitoris. However, reaching the nerve of theclitoris may require a slightly different shaped needle 30 toappropriately position a lead adjacent to the nerve.

FIG. 11 is a flow chart illustrating a technique for performing teststimulation for determining the correct placement of an electrical lead.Test stimulation may be completed with a test stimulation device coupledto implant tool 24 or with implant tool 88. Both test stimulationdevices may be similarly operated. For purposes of illustration, implanttool 88 will be described.

Either before the transobturator procedure is performed or once needle94 is located adjacent to pudendal nerve 40, the physician sets teststimulation parameters (134). Example parameters that may be set includecurrent amplitude, voltage amplitude, pulse width, pulse frequency, orother parameters associated with stimulation of pudendal nerve 40. Ifimplant tool 88 is configured for bipolar stimulation (136), thephysician proceeds to position needle 94 adjacent pudendal nerve 40. Ifimplant tool 88 is not configured for bipolar stimulation, such asunipolar stimulation, the physician must attach ground pad 98 to thepatient and to implant tool 88 (138).

The physician positions needle 94 to a preferred location adjacentpudendal nerve 40 (140) and performs the test stimulation (142). Thephysician may look for good muscle activity associated with appropriatepudendal nerve 40 capture (144). If there is not good capture, thephysician may reposition needle 94 (140). Alternatively, the physicianmay look for appropriate CMAP results from the test stimulation (146).If the CMAP results are not ideal, the physician may reposition needle94 (140). In some embodiments, the physician may observe both muscleactivity and CMAP results before accepting needle 94 location.

If the physician observes good muscle activity or good CMAP results, thephysician may remove needle 94 from cannula 64 (148). Once needle 94 isremoved, the physician may insert a lead and stylet into cannula 64 tofinalize the implantation of the lead adjacent to pudendal nerve 40.

In some embodiments, the method of providing test stimulation withimplant tool 88 may be used to provide test stimulation to other nerves.For example, implant tool 88 may be used to provide test stimulation tothe nerve of the clitoris or other pelvic floor nerve.

FIG. 12 is a functional block diagram illustrating various components ofimplantable drug delivery device 152 for providing neurostimulation. Asshown in FIG. 12, delivery device 152 includes processor 154, memory156, infusion pump 158, telemetry interface 162, and power source 164.Delivery device 152 is implanted within patient 12 or located externallyon patient 12. Catheter 160 is coupled to infusion pump 158 andimplanted adjacent to a pelvic floor nerve, such as pudendal nerve 40.Catheter 160 may be implanted within patient 12 using implant tool 24,and the transobturator technique described herein. For example, catheter160 may be introduced through the lumen of a needle or cannula deployedby the transobturator approach described herein. In some cases, cannula64 may also be used to implant catheter 160 in the appropriate position.Accordingly, the lumen of cannula 64 or needle 30 may be sized toaccommodate a catheter 160. Catheter 160 may be tunneled within patient12 to an implanted device 152 or tunneled transcutaneously to anexternal delivery device 152.

Processor 154 controls the amount of drug dispensed by infusion pump 158to patient 12. Processor 154 may use instructions stored within memory156 to determine the time, amount, and frequency of drug deliverythrough catheter 160. Memory 156 may also store data related to thedispensing of drugs by infusion pump 158. Infusion pump 158 maycontinuously or periodically pump a liquid drug to patient 12. Telemetryinterface 162 may communicate with an external program (not shown) todownload new delivery instructions or upload delivery data. Power source164 may include a rechargeable battery or induction coil produce powernecessary for delivery device 152 operation.

FIG. 13 is a schematic diagram illustrating an exemplary leadlesselectrical stimulation module 166 for electrical stimulation of a nerve.Stimulation module 166 includes implantable housing 168, circuit board170, power supply 172, electrode 174, and electrode 176. Simulationmodule 166 may be implanted within patient 12, adjacent to a pelvicfloor nerve, such as the pudendal nerve. Stimulation module 166 containsall necessary components to provide complete stimulation therapy withoutany lead or other wire connected to the module. Stimulation module 166may be implanted using devices and techniques as described in thisdisclosure, including transobturator introduction techniques.

Housing 168 is biocompatible and protects the components of stimulationmodule 166 from corrosive biological fluids and tissues. Housing 168 maycontain fixation mechanisms similar to lead 46 to secure stimulationmodule 166 near a desired nerve location. Circuit board 170 includescomponents such as a processor, memory, telemetry circuitry, or otherelectronics necessary for performing electrical stimulation. Powersource 172 includes a battery or rechargeable battery to power theelectrical circuitry of stimulation module 166. Power source 172 mayalso generate power through a trickle charger utilizing patient motionor induction with an external device. Electrodes 174 and 176 areattached to housing 168 and may be either a cathode or anode to provideelectrical stimulation. In some embodiments, stimulation module 166 mayinclude more than two electrodes. Alternatively, electrodes 174 or 176may be tethered to housing 168 with a lead. In some embodiments,multiple leadless stimulation modules 166 may be implanted within thepelvic floor using devices and techniques as described in thisdisclosure.

FIG. 14 is a schematic diagram illustrating implantation of leadlessstimulation module 166 through cannula 64. The inner lumen of cannula 64may be sized to accommodate placement of module 166 through the innerlumen. Stimulation module 166 may be small enough to slide through thelumen of cannula 64 and implanted adjacent to pudendal nerve 40.Alternatively, stimulation module 166 may be implanted in tissueadjacent any pelvic floor nerve to provide stimulation therapy.

In other embodiments, stimulation module 166 may be implanted throughneedle 30 without cannula 64. In some cases, a guide wire or stylet maybe used to aid in placing stimulation module 166 in an appropriatelocation. In addition, more than one stimulation module 166 may beplaced adjacent to a nerve for effective stimulation therapy.

Various embodiments of the disclosure may include processors that arerealized by microprocessors, Application-Specific Integrated Circuits(ASIC), Field-Programmable Gate Arrays (FPGA), or other equivalentintegrated or discrete logic circuitry. The processor may also utilizeseveral different types of data storage media to store computer-readableinstructions for device operation. These memory and storage media typesmay include any form of computer-readable media such as magnetic oroptical tape or disks, solid state volatile or non-volatile memory,including random access memory (RAM), read only memory (ROM),electronically programmable memory (EPROM or EEPROM), or flash memory.

Many embodiments of the disclosure have been described. Variousmodifications may be made without departing from the scope of theclaims. These and other embodiments are within the scope of thefollowing claims.

The invention claimed is:
 1. A method comprising: introducing a toolthrough skin of a pubic area between a vagina and an adjacent leg of apatient; positioning at least a portion of the tool through an openingin a pelvis to a target nerve site within the patient; and implanting amedical device at the target nerve site through a path that terminateswithin the patient created by the tool.
 2. The method of claim 1,wherein the opening in the pelvis comprises an obturator foramen.
 3. Themethod of claim 1, further comprising inserting the tool through tissuelateral to a pubic symphysis of a pelvis of the patient.
 4. The methodof claim 1, wherein the implantable medical device includes a lead. 5.The method of claim 1, wherein the implantable medical device includes aleadless stimulation module.
 6. The method of claim 1, wherein theimplantable medical device includes a drug delivery catheter.
 7. Themethod of claim 1, further comprising placing a distal tip of the tooladjacent to a pudendal nerve or a branch of the pudendal nerve.
 8. Themethod of claim 7, wherein placing a distal tip of the tool includesslightly retracting a needle of the tool once the needle contacts asacro-tuborosity ligament beyond the pudendal nerve.
 9. The method ofclaim 1, further comprising delivering electrical stimulation via thetool to verify placement of a distal end of the tool adjacent the nerve.10. A method comprising: introducing a tool into a patient lateral to apubic symphysis of a pelvis of the patient; creating a path through anopening in the pelvis with the tool and positioning at least a portionof the tool at a target nerve site within the patient, wherein theopening in the pelvis is an obturator foramen, and wherein the pathterminates within the patient; and implanting a medical device at thetarget nerve site through the path.
 11. The method of claim 10, whereinthe implantable medical device includes a lead.
 12. The method of claim10, wherein the implantable medical device includes a leadlessstimulation module.
 13. The method of claim 10, wherein the implantablemedical device includes a drug delivery catheter.
 14. The method ofclaim 10, wherein the target nerve site comprises a tissue siteproximate to at least one of a pudendal nerve or a branch of thepudendal nerve.
 15. The method of claim 14, further comprising placing adistal tip of the tool adjacent to the pudendal nerve or the branch ofthe pudendal nerve.
 16. The method of claim 15, wherein placing a distaltip of the tool includes slightly retracting a needle of the tool oncethe needle contacts a sacro-tuborosity ligament beyond the pudendalnerve.
 17. The method of claim 10, further comprising deliveringelectrical stimulation via the tool to verify placement of a distal endof the tool adjacent the nerve.